The present invention relates generally to interface devices between humans and computers, and more particularly to computer interface devices that provide force feedback to the user.
Computer systems are used extensively in many different industries to implement computer controlled simulations, games, and other application programs. More particularly, these types of games and simulations are very popular with the mass market of home consumers. A computer system typically displays a visual environment to a user on a display screen or other visual output device. Users can interact with the displayed environment to play a game, experience a simulation or virtual reality environment, or otherwise influence events or images depicted on the screen. Such user interaction can be implemented through the use of a human-computer interface device, such as a joystick, "joypad" button controller, mouse, trackball, stylus and tablet, or the like, that is connected to the computer system controlling the displayed environment. The computer updates the simulation or game in response to the user's manipulation of an object such as a joystick handle or mouse, and provides feedback to the user utilizing the display screen and, typically, audio speakers.
In some interface devices, tactile and/or haptic feedback is also provided to the user, more generally known as "force feedback." These types of interface devices can provide physical sensations to the user manipulating a user manipulable object of the interface device. For example, the Force-FX controller from CH Products, Inc. and Immersion Corporation may be connected to a computer and provides forces to a user of the controller. Typically, motors or other actuators are coupled to the user object and are connected to the controlling computer system. The computer system can provide forces on the object in conjunction with simulation/game events by sending control signals to the actuators. The computer system can thus convey physical force sensations to the user in conjunction with other supplied feedback as the user is grasping or contacting the object of the interface device. Force feedback interface devices can thus provide a whole new modality for human-computer interaction.
Force feedback input/output (I/O) devices of the prior art have concentrated on providing maximum haptic fidelity, i.e., the realism of the tactile feedback was desired to be optimized. This is because most of the force feedback devices have been targeted at the specific needs of highly industrial applications, and not a mass consumer market. To attain such realism, mass market design concerns have been sacrificed in the prior art.
One consumer market design concern that is always present in force feedback devices is the size, weight, and power consumption of actuators included in the device. To provide realistic high magnitude forces, large and heavy actuators have necessarily been used in non-mass-market force feedback devices of the prior art. However, in the consumer market, such large and heavy actuators are a major drawback, since consumers would prefer a portable, small interface device that can easily fit on a desktop or other small working space. Even more significantly, such large actuators prevent producing a force feedback interface device at a low enough cost to be acceptable to mass market consumers. In the prior art, however, smaller actuators were not an option if realistic forces were to be presented to the user.
Some mass market force feedback devices of the prior art, nevertheless, have been provided, and these devices typically include small actuators to reduce costs. However, force feedback devices with small actuators have a problem in that they may not allow the superposition of many types of force effects due to a limited dynamic range available from the actuators. For example, if a jolt feel sensation is desired to be superimposed on a vibration feel sensation to the user, then the force magnitudes of the two feel sensations are added together. However, if the maximum available dynamic range of the actuators is small, as is typically the case for mass market force feedback devices, then the realism of the feel sensations must be sacrificed in some way to accommodate both feel sensations. For example, the jolt sensation would have to be reduced in magnitude, thus reducing the effectiveness of that feel sensation to the user. Providing actuators with a greater dynamic range typically means providing larger, more expensive actuators, which is not usually feasible in the consumer market as explained above.
In addition, there is unnecessary complexity in the manipulation of force feedback signals in the prior art. To produce a feel sensation to a user of the force feedback device, a force signal of the prior art must include all information required to realistically output that feel sensation to the user. However, the computational burden of providing feel sensations to a user can be high, especially when providing multiple simultaneous feel sensations. To adequately provide the desired forces, complex and expensive components typically must be included in the force feedback device, often pushing the cost of realistic force feedback out of the reach of mass market consumers.